Balance spa water without the guesswork.

Enter your latest strip or drop-test readings, get a priority order, estimate sanitizer additions, and keep a simple history on the phone.

Install on this device

Open this from a hosted web link, then use Install app. On iPhone or iPad, use Share and Add to Home Screen.

Phone or tablet

  1. Open the hosted app link in your browser.
  2. On Android, tap Install app or Add to Home screen.
  3. On iPhone or iPad, tap Share, then Add to Home Screen.

PC or laptop

  1. Open the hosted app link in Chrome or Edge.
  2. Use the install icon in the address bar, or choose Install app from the browser menu.
  3. The app will then appear in your Start menu or app launcher.

Start Here

3 simple steps

No chemistry knowledge needed. Copy the numbers from your strip or drop-test kit, then let SpaChem put them in order.

1

Tub size

Enter the water volume once and save it.

2

Test strip

Type the numbers you can read. Leave defaults if your strip does not show one.

3

Analyse

Tap Analyse and follow the first priority action.

When in doubt, do less and retest. Add one product at a time, keep the pump running, and keep bathers out if water is cloudy or sanitizer/pH is out of range.

Water Setup

Ready
Not saved yet

Latest Readings

ppm unless shown

Add your readings

The assistant will rank the next steps and flag unsafe combinations.

Priority Actions

Retest after circulation

Safety Rules

  • Never mix chemicals together outside the water.
  • Add one chemical at a time with pumps running, then retest.
  • Keep bathers out when sanitizer or pH is outside the safe range.
  • Follow the chemical label where it differs from this assistant.
  • Drain and refill if stabiliser or dissolved solids are persistently high.

Troubleshooting Guide

Fix the cause, then retest

Cloudy water

Keep bathers out until the water is clear. Check pH and sanitizer first, rinse the filter, run circulation, and shock or oxidise only according to the product label. If stabiliser, hardness, or dissolved solids are high, a partial drain and refill may be the cleanest fix.

Foaming

Foam usually comes from body oils, detergents, cosmetics, or old water. Rinse swimwear without detergent, shower before bathing, rinse the filter, and check pH/alkalinity. Anti-foam is a short-term rescue; persistent foam often means it is time to change water.

Low chlorine or bromine

Do not use the tub until sanitizer is back in range. Balance pH first, then dose sanitizer with pumps running. If the level keeps disappearing, clean the filter, shock/oxidise, check for heavy bather load, and confirm the test strips are fresh.

Strong chlorine smell

A strong smell often means used-up sanitizer by-products, not necessarily too much free chlorine. Test before adding anything. If free sanitizer is low or combined contamination is suspected, oxidise/shock as directed and leave the cover open while circulating.

pH keeps bouncing

Check total alkalinity before chasing pH. Low alkalinity lets pH swing; high alkalinity can hold pH up. Adjust alkalinity in stages, circulate, and retest before making another change.

Green tint or slippery surfaces

Treat this as a no-bathing warning. Check sanitizer and pH, brush surfaces, clean the filter, and shock/oxidise as directed. If it does not clear quickly, drain, clean, and refill.

Recommended Weekly Routine

Simple habits, fewer surprises

Before each use

  • Check sanitizer and pH.
  • Do not bathe if water is cloudy.
  • Shower first to reduce foam and demand.

After busy use

  • Run the pump with the cover open.
  • Retest sanitizer after circulation.
  • Top up sanitizer if it has dropped low.

Once a week

  • Test the full strip panel.
  • Rinse the filter thoroughly.
  • Wipe the waterline and underside of cover.

Weekly balance

  • Adjust alkalinity before fine-tuning pH.
  • Shock or oxidise if the label recommends it.
  • Log the reading so trends are visible.

Every month

  • Deep clean or replace filters as needed.
  • Inspect jets, cover, and waterline.
  • Check strips are still in date and dry.

Every 2-3 months

  • Drain and refill domestic spas as needed.
  • Clean shell surfaces before refilling.
  • Restart balance from alkalinity, then pH.

Sanitizer Dose Estimate

For chlorine granules or liquid chlorine only. Bromine tablets and pH products vary too much for a safe generic dose.

0 g

Estimate updates from your volume and target increase.

Target Ranges

Hot tub pH7.2-7.8
Hot tub free chlorine3-5 ppm
Hot tub bromine4-6 ppm
Total alkalinity80-120 ppm
Calcium hardness150-250 ppm

Ranges are practical defaults. Manufacturer guidance and local regulations should win for public/commercial water.

Generic Strip Colour Chart

Fallback only

Use this only when the bottle chart is missing. Test strip brands vary, lighting changes colours, and old strips drift, so confirm with a fresh kit before dosing heavily.

pH

Target 7.2-7.8
6.8low
7.2ok
7.4ok
7.8ok
8.2high
8.4high

Free chlorine

Spa target 3-5 ppm
0empty
1low
3ok
5ok
10high
20very high

Bromine

Spa target 4-6 ppm
0empty
2low
4ok
6ok
10high
20very high

Total alkalinity

Target 80-120 ppm
40low
80ok
120ok
180high
240high
360very high

Calcium hardness

Spa target 150-250 ppm
0soft
100low
150ok
250ok
500high
1000very high

Cyanuric acid

Spa usually under 50 ppm
0none
30ok
50limit
100high
150high
300very high

Suggested Chemicals

Some product links are affiliate links. If you buy through them, we may earn a small commission, but the price you pay does not increase. Always check the product label is suitable for your spa, pool, and sanitizer system before dosing.

Chlorine granules: Clearwater 1kgBUY
Bromine tablets: ClearSpa 5kgBUY
pH increaser / reducer: Happy Hot Tubs bundleBUY
Alkalinity increaser: ClearSpa 1kgBUY
Replacement test strips: AquaChek 7-way, 100 stripsBUY

Reading History